Sediment connectivity, defined as the degree of linkage between the sediment sources to downstream areas, is one of the most important properties that control landscape evolution in river basins. The ...degree of linkages amongst different parts of a catchment depends mainly on the hinterland characteristics (e.g. catchment morphology, slope, shape, relief, and elevation), channel characteristics (e.g. slope, stream network density, valley confinement), and the combined effects of vegetation (e.g. land use changes and land abandonment). This paper evaluates the sediment connectivity of the upper Kosi basin covering an area of ~52,731 km2 including Tibet and Nepal at different spatial scales. We have computed the index of connectivity (IC) using the equations originally proposed by Borselli et al. (2008) and modified by Cavalli et al. (2013) to evaluate the potential connection of sediment source areas to the primary channel network as well to the catchment outlet. Our results highlight significant spatial variability in sediment connectivity across the basin and provide important insights on structural sediment dynamics in a complex geological and geomorphological setting. We compare our results with the observed sediment load data at certain outlets and demonstrate that sediment flux in different sub-basins is controlled by variable slope distribution and land use and land cover that are strongly related to the structural connectivity. We argue that IC model can be extremely beneficial to understand sediment dynamics at catchment scale in a large river basin (~103–104 km2 scale), where systematic field investigations for mapping hillslope-channel linkages are not feasible.
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•Sediment connectivity in a large basin a function of LULC, slope and basin shape•Integration of stream power with catchment connectivity to understand sediment dynamics•Connectivity analysis compares well with measured sediment fluxes at the outlets.•Spatial correspondence of IC with rainfall useful to explore functional connectivity
Novel FeAgPt alloy nanoparticles were biosynthesized via ultra-sonication using the root extract of Platycodon grandiflorum. The nanoparticles exhibited enhanced catalytic activities in the reduction ...of 4-nitroaniline (4-NA) to p-phenylenediamine with a significantly reduced reaction time and increased rate constant because of their high number of active surface sites. In addition, the same catalyst exhibited enhanced catalytic activity in the decolorization of an environment polluting dye, rhodamine B (RhB). The time taken for the complete conversion of 4-NA to p-phenylenediamine was 25 min with an apparent rate constant of 10.06 × 10−2 min−1. Similarly, the catalytic decolorization of RhB took 15 min for complete decolorization of the dye molecules with a rate constant 25.60 × 10−2 min−1. The performance difference of mono, bi and trimetallic nanoparticles for both the reduction of 4-NA and decolorization of RhB was also examined. These trimetallic alloy nanostructures with excellent catalytic efficiency can also be used for other applications.
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•FeAgPt alloy nanoparticles were prepared using a green method via ultrasonication.•The synthesized nanoparticles were well characterized by XRD and TEM.•The alloy nanoparticles showed the best catalytic reduction activity compared to mono and bimetallic nanoparticles.
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•Sediment dynamics of a large tropical river in the Ganga basin.•Annual deposition of ∼20–50 MT of sediments in different reaches.•High sediment flux linked to channel instability and ...frequent flooding.•Human interventions have affected sediment dynamics significantly.•Sediment dynamics is the most important river management issue in the Kosi basin.
Hydrological and sediment transport characteristics for the Kosi basin, which covers parts of Nepal and India, were analysed to understand the spatiotemporal variability of the hydrology and sediment dynamics of the Kosi basin and its implications for flood hazard and sediment dynamics. The study revealed that ∼56% of the discharge at Chatara (where all major tributaries of the Kosi meet) is contributed from the western part of the basin even though this constitutes only 34% of the total basin area. In contrast, the central and eastern parts of the basin constitute 57% and 8% of the basin area but contribute ∼38% and ∼16% of the discharge at Chatara, respectively. The contribution of sediment load at Chatara from the different tributaries of the Kosi River also shows a similar pattern. Of a total of ∼100 million tonnes of the annual sediment load at Chatara, ∼56% is transported from four tributaries: the Indrawati, Bhote Kosi, Tama Kosi (all draining from the west), and Tamor. The remaining ∼44% is transported by other tributaries upstream of Chatara, the most important being the Arun, Dudh Kosi, and Sun Kosi. Sediment budgeting in this study, based on annual sediment load data, suggested that ∼20 million tonnes of sediments are deposited between Chatara and Birpur annually. This study also found that ∼53 million tonnes of sediments are being accommodated between Birpur and Baltara annually. Sediment dynamics in the Kosi basin emerges as the most important river management issue, and this is closely linked to channel instability and frequent flooding in the alluvial plains.
•A novel method to derive distribution of stream power (SP) utilising a physically-based hydrological model (SWAT).•SWAT derived hydrological variability was used to derive the basin scale specific ...stream power (SSP) distribution pattern.•Stream power distribution along tributaries shows multiple peaks which relate to erosion rates and geomorphic processes.•Monsoonal rainfall determines SP and SSP peaks which are 100–1500 times greater in monsoon than in non-monsoon periods.
River processes in a drainage basin are strongly governed by the spatio-temporal variability in stream power. Recently, various approaches have been developed to derive the spatial variability of stream power in a river basin; however, the temporal variability in stream power due to hydrological changes remains poorly understood. An assessment of the temporal variability of stream power is critical for river studies in monsoonal regimes because significant geomorphic work is performed during this period, particularly in the Himalayan rivers. This paper presents a novel methodology to derive the stream power distribution at a basin-scale using a physically-based-hydrological model, the Soil and Water Assessment Tool (SWAT). Hydrological changes in the upper Kosi (also called Koshi) basin in the Central Himalaya were analysed and integrated with slope variability and channel width to obtain the basin-scale distribution of total stream power and specific stream power. Most of the tributaries of the Kosi River are characterized by a multi-peak distribution of stream power. Stream power distribution in the basin shows no systematic downstream increase or decrease of either total stream power or specific stream power. Total and specific stream power peaks during the monsoon period are 100–1500 times higher compared to the non-monsoon period and exceed the threshold for erosion and sediment transport processes. The SWAT model also helped to assess controls on the stream power distribution in the basin. The downstream distribution of stream power between confluence points is influenced by slope variability, while major increases at confluence points are due to discharge variability. Geological characteristics control the spatial distribution of stream power while the annual rainfall distribution influences the seasonal variability of stream power.
Background
Hepatitis‐E virus (HEV) is an emerging infectious threat to blood safety. The enormity of the transmission of HEV and its clinical consequence are issues currently under debate. This study ...aimed to evaluate the prevalence of HEV‐RNA in blood donors in western India.
Materials and Methods
We screened 13 050 blood donors for HEV using HEV‐RNA screening of 10 mini‐pools using RealStar HEV RT‐PCR Kit (95% limit of detection (LOD): 4.7 IU/ml). Furthermore, all HEV‐RNA‐positive donors were investigated for the presence of IgM/IgG antibody along with liver function tests.
Results
Of the 13 050 blood donations, 7 (0.53%) were found to be HEV‐RNA positive, and the prevalence of HEV nucleic acid testing yield cases among blood donors was 1 in 1864. All seven HEV‐RNA‐positive samples were tested with anti‐HEV IgM and anti‐HEV IgG antibodies; this resulted in two (28.5%) positive anti‐HEV IgM and two (28.5%) positive anti‐HEV IgG antibodies. Hepatic activity was measured, with two of seven HEV‐RNA‐positive donors demonstrating abnormal serum glutamic oxaloacetic transaminase (SGOT) andserum glutamic pyruvic transaminase (SGPT). Two HEV‐RNA‐positive blood donors who had abnormal SGOT and SGPT were found to have a high HEV viral load. Furthermore, we were able to follow up two HEV‐RNA donors, and both were HEV‐RNA positive and had anti‐HEV IgM and anti‐HEV IgG antibodies; moreover, their liver function tests were also abnormal. One of the HEV‐RNA donors with high viral load did show hepatitis‐E‐like virus on electron microscopy.
Conclusion
Our studies indicate that there is a significant risk of blood‐borne transmission of HEV. This finding may help to provide a direction towards the safety of blood transfusions in clinical settings in countries like India, which fall under the endemic category for HEV infection.
•Flood risk assessment by estimating flood hazard and vulnerability separately in Kosi megafan region, India.•Use of multi-decision making criteria for flood risk assessment in a GIS framework.•About ...67 % of the Kosi megafan is prone to flood hazard out of which 62 % falls in high risk zone.•Advocates soft engineering solutions for flood management and flood risk reduction.
Floods are one of the most devastating natural events that lead to enormous and recurring loss of life, properties, and resources around the globe. In India, floods remain a major hazard during the monsoon season in many parts of the country but most seriously in the flat and monotonous Gangetic plains in the Himalayan foreland. One of the most flood-prone rivers in India is the Kosi in north Bihar, eastern India, which also forms the largest active megafan in the world. The Kosi River is known as the “sorrow of Bihar” because of its anomalous behavior and the damage it causes due to frequent floods in this region. This study evaluates the flood hazard and flood vulnerability as separate entities and combines them to assess the flood risk in the Kosi megafan region. Geomorphological, hydrological, and socio-economic data have been integrated in a GIS framework using a multi-criteria decision tool called the Analytical Hierarchy Process (AHP) to generate a process-based flood risk map for 105 blocks (administrative units) of both Nepal and India (Bihar). Such maps should encourage soft engineering solutions for flood mitigation aimed at minimizing the consequences of flooding and reducing flood risks. This study has significant implications for developing measures and plans that will help government and relief agencies in the identification of flood-prone areas and for planning emergency management strategies in this region.
A novel magnetically recoverable hematite nanoparticles (α-Fe2O3 NPs) was fabricated by a simple, one pot, and green method using the rhizome of Cyperus rotundus L., as a reducing and stabilizing ...agent. The prepared nanoparticles were well characterized by all parameters. TEM showed that the hematite nanoparticles had a rhombohedral shape and ranged in size from 80 to 100 nm. The phase study of the α-Fe2O3 nanoparticles was confirmed by Raman spectroscopy. In addition, the synthesized nanoparticles shows good photocatalytic activity in degradation of highly toxic Congo red dye within 25 min, and the same NPs exhibits higher catalytic activity for the reduction of 4-nitro-o-phenylenediamine (4-NPD) to 1,2,4-benzenetriamine in the presence of NaBH4 within 12 min. After the reaction, the catalyst was recovered and reused three times without significant loss of catalytic activity.
A modified method is described for the preparation of amino-functionalized covalent organic framework nanosheets (COF-NSs). These consist of hexagonal layered sheets and were prepared from ...commercially available starting materials (p-phenylenediamine and benzene-1,3,5-tricarboxaldehyde). The interlayer stacking interactions between the ultra-thin COF-NSs became weak because the π stacking is destroyed by sonication. This result in the exfoliation of COF-NSs. As an application, the COF-NSs used for sensitive and selective fluorometric determination of DNA. To reach this goal, H1 and H2 hairpin-like DNA probes were chosen; H1 used Texas Red-labeled dye as a fluorescent probe. The addition of the COF-NSs, the hairpin probes was adsorbed onto the porous surface of the COFNSs. The π stacking and hydrogen-bond interactions between COFNSs and nucleic acid quench the fluorescence of the Texas red-labeled probe. The target DNA enables the recovery of the quenched fluorescence of the Texas red-labelled probe by triggering an inter-chain hybridization within hairpin probes. This results in a weaker interaction of double-stranded DNA (dsDNA) with the COFNSs. Consequently, the dsDNA detaches from the COFNSs, thereby recovering the dye’s fluorescence (excitation/emission maxima at 590/612 nm) with increasing target DNA concentration. The findings were applied to design a method for the determination of DNA that has a 2 pM detection limit. This is significantly lower than the limit of detection reported previously for 2D nanomaterial-based fluorometric DNA assays.
Graphical abstract
Schematic representation of 2D-covalent organic framework nanosheets (COF-NSs) probe act as a quencher allowing the highly sensitive and selective fluorescence turn-on detection for biomolecules. Here the H1 H2 are hairpin DNAs. H1 is associated with the fluorescent tag (red circle), while the "fluorescence off" state it denoted as a black circle.
Nucleic acid amplification testing (NAT) is restricted to a few blood banks in India since 2008. This review was directed toward understanding NAT yield in different parts of the country and ...prevalence in the NAT of different types of virus.
English literature was searched from 1990 to 2016 in PubMed, Scopus, Ind med, and Google database using properly constructed key words. Literature was collected and finally the data were synthesized.
NAT results from 11 publications and one personal communication showed that till date 389387 blood units have been NAT tested from various parts of the country. NAT yield varied from 1:476 to 1:4403 in various studies. Till date, 58/2550 (2%) blood banks of India are doing NAT testing but all of them have not published their results. Majority of the centers have used ID-NAT (Individual NAT) protocol and 21 blood banks are using minipool format of the test. One center has used in-house NAT testing system. In> 70% of the time, the NAT positivity with due to hepatitis B (Hep B). For individual infection, NAT yield from the pooled data showed HIV in 1:66,000, Hep C virus 1:5484 and Hep B in 1:1761 seronegative donors.
In view of the very high NAT yield (1:1361), NAT in some from needs to be universally applied in Indian blood banks. However, the high Hep B occult infection suggests stricter donor selection and immunization of adults for Hep B may be way forward toward ensuring the viral safety of blood components in India.
β-thalassaemia is a group of inherited single-gene disorders worldwide. Each ethnic population has its own common mutations. Heterogeneity of β-thalassaemia mutations in multi-ethnic population of ...Surat, makes molecular diagnosis expensive and time consuming.
Specific primers were used to differentiate four common mutations, IVS I-5 (G→C), Codon 41/42 (- TCTT), 619-bp deletion and FS 8/9 (+G), by a simple PCR involving a multiplex amplification refractory mutation system.
Several high prevalence β-Thalassemia trait groups constituted by Muslims, Patels, Sindhis, ModhBanias, and Mahayavanshi. Four most common mutations detected in them are IVS I-5 (G→C), Codon 41/42 (- TCTT), 619-bp deletion and FS 8/9 (+G). We identified each of these β-thalassemia mutations in multiplexed ARMS from positive control samples. Our multiplex-ARMS-PCR system was first standardized on positive DNA samples with above known four most common β-thalassemia mutations, and these positive samples had been diagnosed with β-thalassemia and also all these samples belonged to Surat ethnic groups. The system was subsequently tested on 110 blood samples from different ethnic backgrounds with unknown β-thalassemia mutations which were in all specimens.
The ARMS multiplex system was found reliable, cost effective, fast and most applicable for mutation screening of Thalassemia in Surat populations.
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